Quotes by Certain Knowledge Knowledge is recognizing what you know and what you don't. Confucius certain-knowledge homeschooling education It is therefore worthwhile, to search out the bounds between opinion and knowledge; and examine by what measures, in things, whereof we have no certain knowledge, we ought to regulate our assent, and moderate our persuasions. John Locke certain-knowledge persuasion opinion Not to understand the doer is to have no certain knowledge of what has been done, or why it was undertaken Philip Wylie certain-knowledge doers done Americans live with the certain knowledge that the source of their greatness has not yet been released. Ralph Steadman certain-knowledge source greatness